This invention relates generally to electronic circuits, and more particularly to a temperature monitoring circuit.
Often in circuit designs and applications, it is useful or even critical to be able to monitor the temperature of a circuit in operation under various operational modes or environments. If electronic components become too hot, their performance may deteriorate, or the components may even be destroyed. Furthermore, the overall system in which a circuit is used can be optimized by monitoring the temperature, increasing system performance. Prior art methods of sensing or monitoring temperature are large and expensive, prohibiting use in many applications. For example, temperature monitor circuits designed for printed circuit motherboards consume a great deal of surface area and are quite costly.
FIG. 1 illustrates an example of a temperature-sensitive electronics application, a case or tower 10 for a personal computer comprising a central processing unit (CPU) (not shown). The tower 10 comprises a plurality of modules 12, 14, 16 for electronic storage of data for a personal computer. The modules may comprise, for example, a compact disk drive module 12, removable 3.5xe2x80x3 disk drive module 14, and a hard-disk drive module 16. The tower 10 also comprises other circuit boards and connectors for communicatively coupling to a monitor, keyboard, printer, Internet and/or LAN, and other devices and equipment, not shown.
The hard-disk drive module 16 is particularly sensitive to high temperatures. The hard-disk drive module 16 typically comprises a sealed metal box having no air flow from the outside to the inside or vice versa, making it difficult to dissipate thermal energy. The electronic components of the hard-disk drive module 16 may reach high temperatures when the disk drive 16 is in operation. More recent hard-disk drive designs are faster and more powerful, thus reaching higher temperatures than before.
What is needed in the art is an integrated circuit or chip-level circuit and method of monitoring temperature.
The present invention achieves technical advantages as a digital temperature monitor circuit and method particularly beneficial for on-chip temperature monitoring in a hard-disk drive preamplifier system. A proportional-to-absolute temperature (PTAT) sensor and a reference circuit are coupled to a comparator. The PTAT sensor provides an output voltage that is a function of and proportional to the absolute temperature. The comparator is adapted to compare the voltage of the reference circuit to the PTAT sensor voltage and determine the temperature of the PTAT sensor, adjacent or proximate integrated circuit devices, or the ambient temperature.
Disclosed is a digital temperature monitor (DTM) comprising a comparator having a first and second input terminal. A PTAT sensor is coupled to the comparator first input terminal and a reference circuit is coupled to the comparator second input terminal. The comparator is adapted to compare the voltage of the reference circuit to the voltage of the PTAT sensor to determine the integrated circuit temperature.
Also disclosed is a preamplifier circuit for a hard-disk drive storage device, the preamplifier circuit comprising a DTM. The DTM includes a comparator having a first and second input terminal and a PTAT sensor coupled to the comparator first input terminal. A reference circuit is coupled to the comparator second input terminal. The comparator is adapted to compare the voltage of reference circuit to the voltage of PTAT sensor to determine the temperature of the preamplifier circuit.
Further disclosed is a method of detecting the temperature of an integrated circuit. The integrated circuit includes a comparator having a first and second input terminal. A PTAT sensor having an output voltage is coupled to comparator first input terminal, and a reference circuit is coupled to the comparator second input terminal. The method includes the steps of providing a reference signal, increasing the reference signal, and determining the temperature of integrated circuit when reference signal is greater than the PTAT sensor output voltage.
Advantages of the invention include a real estate savings for electronic circuitry, and a cost-effective circuit and method for detecting or monitoring the temperature of an electronic circuit. The digital temperature monitor of the present invention is preferably implemented integral to or as part of an integrated circuit, requiring few additional components in the application. The number of circuit elements required in the integrated circuit is minimal, including the PTAT sensor and a few logic gates along with a comparator. The transistors, gates, and other elements of the reference circuit may be xe2x80x9cborrowedxe2x80x9d or multiplexed by switching from other circuit components of the integrated circuit using the invention. An electronic application such as a hard-disk drive may be monitored for excessive temperatures and shut down when a predetermined temperature threshold is reached to avoid damage to electronic components and prevent erroneous results. The read and write performance of a hard-disk drive preamplifier may be optimized with the use of the present digital temperature monitor.